bar bending schedule for a classroom block in mengo senior secondary school
UJI BENDINGDeskripsi lengkap
Pure Bending
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AK Receiver Bending From a Tapco Flat
A tutorial by 1952Sniper February 2006
(originally posted on http://www.ssboards.!o" http://www.ssboards.!o" by by 1952Sniper# $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ % de!ided to write this this tutorial a&ter ha'ing spent a day and a hal& bending re!ei'ers. re!ei'ers. %t "ight be a help to those o& you you who are interested in bending your your own re!ei'ers &ro" a &lat. &lat. ysel& and another &oru" "e"ber (%)ll let hi" !hi"e in i& he wants to identi&y hi"sel&# did a whole pro'erbial s***$load o& the"+ and % now now "ore about the pro!ess than % e'er wanted to+ ,-,. % won)t pretend it)s the be$all end$all o& bending re!ei'ers. re!ei'ers. %t)s ust "y "y eperien!e+ and a good starting point. ou guys that ha'e used other "ethods and other bending &itures+ &eel &ree to !hi"e in and add in&o. For starters+ it)s a lot o& &un. &un. %& you)re only bending a !ouple+ it)s a relati'ely si"ple tas that should tae no ti"e at all. %& you)re doing as "any as we did+ though+ it)s a lot o& wor and needs to be well planned. ou should !ount on &atigue be!o"ing an issue. i'e yoursel& plenty o& ti"e &or breas. And be aware o& when you)re getting getting tired+ be!ause that)s when a!!idents start start to happen. e ha'e the hand inuries and sore li"bs to pro'e it. 3he pro!ess we used too right at 15 "inutes to go &ro" a &lat to a bent re!ei'er+ &ro" start to &inish. 4ut we a'eraged about re!ei'ers &or &or e'ery hours spent. 3hat in!ludes breas+ re$organi7ing tools+ tools+ periodi! !leanup+ et!.+ without &eeling lie we had to rush so "u!h that our 8uality le'el had to su&&er. 4ending a &lat into a re!ei'er should shou ld generally re8uire the &ollowing steps: 1. Asse"ble the inside die around the &lat 2. rease the hell out o& e'erything e' erything . ress it into the outer &or" . S8uee7e the asse"bly in a 'ise to eli"inate possible bowing in the "iddle 5. ;a""er or otherwise bend o'er the upper rails 6. %n'ert the asse"bly and no! out the inside die and re!ei'er <. =isasse"ble inside &or" and no! re!ei'er o&& o& it %)ll go into detail detail on ea!h step. % should note that not all bending igs (&itures# (&itures# are !reated e8ual. 3here are a lot o& di&&erent designs out there+ although they al"ost all basi!ally wor using the sa"e prin!iple. And i& your &iture is !reated to the proper di"ensions+ it should should yield the sa"e results no "atter how it)s put together. 3he result+ o& !ourse+ being a bent re!ei'er that)s ready &or &or &itting/tri""ing &itting/tri""ing and asse"bly to a parts p arts it. 3he &iture we used was one that % bought &ro" a "e"ber o& an A> building board+ and is based on the ernelrin design (&or those o& you who are &a"iliar with that userna"e#. userna"e#. %t wors great and is robust enough to last through a lot o& bends. 4elow is a pi!ture o& the inside &or" (the die# and its asso!iated pie!es+ net to one o& the 3ap!o &lats we were about to bend. %)ll apologi7e in ad'an!e &or the !rappy pi!tures. % had to use "y old old digital !a"era be!ause "y good one was out o& ui!e and % !ouldn)t &ind the !harger. Anyway+ in the pi!ture below you you !an see the upper part o& the die+ the lower plate that sandwi!hes the &lat inside+ bo lts that !la"p it all together+ and two aligner pins with brass nobs on the".
%)ll also pause here to gi'e !redit to the gentle"an that built this bending &iture and sold it to "e. ;e has "ore "ore &or sale sale and is an etre"ely help&ul and &riendly guy. oes by the userna"e s"ittyg o'er on gun!o.net+ and he has epressed interest in selling the" on this board too. %n &a!t+ % see that he)s a "e"ber here. So loo &or &or a post &ro" hi" in the trade/sale &oru"s. ;is bending &iture wored well &or "e and although % ha'en)t used any other types+ % will will say that this this one "ore than "et "y needs. % now se'eral o& you you A> builders are looing &or a bending &iture+ and % !an tell you that s"ittyg will do his best to "ae sure you)re satis&ied satis&ied and answer any 8uestions you you ha'e. Support &or a sold produ!t produ!t goes a long way with "e+ and he)ll de&initely de&initely gi'e support &or his his produ!t. And by the way+ %)" not being being paid &or endorsing his bending &iture. % ust thin he)s got a good produ!t at a good pri!e+ and pro'ides good ser'i!e. A? all around+ around+ and % highly re!o""end his bending &iture.
Step 1: Assemble the die around the flat
-n this parti!ular bending &iture design+ you install the aligner pins through the botto" o& the botto" plate+ then through the aligner holes on the &lat (whi!h are the s"all holes at the 'ery &ront and rear o& the &lat#. 3his is then lined up with the botto" o& the die+ and the aligner pins are inserted there as well. All pie!es will be lined up per&e!tly. @o "easuring or &iddling ne!essary. 3he bolts bolts are then inserted through the top o& the die and they are threaded into the the botto" plate. %t)s i"portant to tighten these bolts &airly tight to ensure that the &lat stays put. 3he bolts rea!h through the eisting openings in the &lat (the pistol grip s!rew hole+ the trigger hole+ and two through the "ag well opening#. 3hey si"ply draw the botto" plate tight to the die. 3hen the aligner pins are re"o'ed. -n!e the aligner pins are re"o'ed+ re"o'ed+ the only thing holding the &lat in align"ent is the !o"pression o& the bolts. bolts. So tor8ue the" down pretty good+ but not tight enough to strip strip threads. ust a &ir" tug with a so!et wren!h is what % did. hen you get the botto" plate on with the &lat installed+ it loos lie this:
@ote that you !an see the botto"s o& the bolts+ and the aligner pins are still in pla!e. 3his botto" plate ser'es se'eral &un!tions as &ar as % !an tell. tell. %t eeps the botto" o& the &lat positioned properly. %t also eeps the botto" &ro" bowing out when the sides are bent+ gi'ing ni!e !risp !orners. %t also ser'es as a guide inside the &or" as it)s pressed in. in. 3he width o& the botto" plate is the sa"e as the width o& the outside o& your re!ei'er a&ter bending. So the re!ei'er walls B&ollowB the botto" plate into the ig.
Step 2: Grease all contact surfaces of the bending fiture
A&ter the aligner pins are re"o'ed+ you)ll want to grease the hell out o& the botto" o& the &lat+ where it will BrideB the the outside &or" when it)s being being bended. e used obil 1 syntheti! grease. %t)s red in in !olor+ as you you !an see below. -thers use ale grease or other inds o& grease. hate'er &loats your your boat. ust "ae sure it)s a good 8uality grease that lubri!ates well. well.
And here)s a pi!ture o& the top o& the die with the &lat installed. %t is i"portant to ,%;3, grease the !onta!t sur&a!es between the inside die and the inside o& the re!ei'er. -therwise you !ould ha'e a hell o& a ti"e getting the re!ei'er o&& o& it later a&ter it)s been bent around all !orners o& the die. % only tried it on!e without grease on the inside o& the re!ei'er+ and had a hard ti"e. So % !ontinued to grease it and didn)t ha'e any "ore proble"s. 4ut do it lightly+ so it isn)t so"ething that)s ha'ing to be s8uee7ed out when you press the die into the outside &or".
%)ll also tae this opportunity to point out the inletting on the die &or the "aga7ine stabili7er di"ples+ and note that they)re slotted so the di"ples !an ride in that !hannel later+ as you re"o'e the !o"pleted re!ei'er &ro" the die. die. 3his die also had an inletted inletted area &or the di"ple di"ple at the sele!tor le'er. %t did not ha'e any inletting &or the C$ ais di"ples or the sele!tor le'er not!h or the bulge around the le&t side sele!tor sele!tor le'er hole. 3he new 3ap!o &lats ha'e all these di"ples on the"+ but they didn)t see" to be a&&e!ted in the bending pro!ess and they &ared ust &ine. So+ be&ore "o'ing on to the third third step+ you)ll want to grease the outside &or" as well. @ot only on top where the &lat will !onta!t it when you start bending+ but espe!ially at the !orners o& the &or" that "ae the &old+ as well as the inside &a!e. 3his is the "ost "ost !riti!al area. %& it)s not greased greased su&&i!iently+
you will get s!arring on the outside o& your re!ei'er as it slides down inside the &or". ou !an see that % ha'e the top and insides o& the &or" greased+ with the asse"bled die sitting upside down+ ready to be &lipped o'er and pla!ed into it. 3oo "u!h grease is better than not enough. 4e generous.
Step !: Bend the sides of the flat up
la!e the asse"bled die into the top o& the outside &or" and !enter it in the &or" so you)re not too !lose to the ends. 3hen !enter the entire entire asse"bly under the ra". =ouble !he! that your your aligner pins are re"o'ed and that e'erything is ready to go.
@ow snug up the ra" to the top+ and start pressing down. %& it)s it)s !entered !orre!tly+ both sides should start to &old up at the sa"e rate+ as you see below.
So"eti"es the sides will gently &old up &lush to the die+ but in "ost !ases % &ound that they would rea!h a point where they BsnapB to the sides+ and the whole shop press goes SD-%@E 3hat)s &ine. ust be aware o& this+ and go slowly when it)s !lose to the point. As you pro!eed &urther+ the sides should be straight up 'erti!ally in the &or"+ tight against the inside die.
>eep pressing it down into the &or" until the top o& the die is at least &lush with the top o& the outside &or". So"eti"es+ as the die is pressed in+ one end will tend tend to go down &aster &aster than the other. % ept sear!hing &or a Bsweet spotB on the top o& the die that would ensure en sure e'en plunging lengthwise+ but ea!h &lat would go in di&&erently. %& one end sins down &irst+ you)ll need to reposition the ra" to try to get the other side side down. ith this parti!ular parti!ular bending &iture+ the bolt heads on top presented a proble". % didn)t want to be pressing on the bolt heads+ so % had li"ited roo" between the "iddle bolts in whi!h to pla!e the ra". hen one end would sin &aster than the other+ we would ha'e to pull the entire asse"bly and turn it 90 degrees so the ra" !ould get all the way to the end o& the die (the shop press &ra"e wasn)t wide enough to si"ply shi&t the &iture to the side &ar enough#. So then+ pressing on the end o& the die and using a pie!e o& bar sto! to shi" up and ensure that the ra" wasn)t tou!hing a bolt head+ we !ould press the high end down into the &or". &or". %t was a si"ple si"ple enough way to do it and wored well. %n the pi!ture below+ you)ll you)ll see what %)" taling about. %n this !ase+ the die die went into the &or" e'enly. e'enly. 4ut sin!e the rear o& the re!ei'er is taller than the &ront+ it be!o"es ob'ious that the rear end o& the die needs to go down &urther into the &or" than the &ront. So that)s what we)re doing doing here+ trying to get it so the top o& our bent re!ei'er is e'en.
As % said+ ea!h &lat would go into the &or" di&&erently. So"eti"es+ when one end was riding high and we)d go to press that end in+ the other end would start li&ting ba! up slightly. -ther ti"es ti"es it wouldn)t. ust play it by ear and adust your ra" position as ne!essary to get the die down into the &or". %t really goes pretty 8ui!ly+ so don)t start thining this is a "aor deal. -n!e the die is pressed down with the top !orners about &lush with the outside &or"+ it)s good to go. 3ae it out o& the press.
Step ": #ompress the sides of the form
=epending on the design o& your outside &or"+ you "ay eperien!e bowing in the "iddle during the pressing operation. % did noti!e a s"all gap in ours+ right at the "iddle o& the re!ei'er. And % "ean s"all lie perhaps a !ouple thousandths o& an in!h. So"e designs "ay not ha'e a noti!eable gap+ but %)d bet you would &ind that it bowed in the "iddle i& you too detailed "easure"ents. %t)s sa&e to assu"e that all &or"s will bow. So the easiest thing to do is ust tae your entire asse"bly asse"bly with the die still in it+ and s8uee7e it tightly in a 'ise to !o"press the sides and sharpen up your botto" !orners o& your your re!ei'er. ou)ll see any gaps !lose right up+ and the grease will s8uee7e out. 3hat "eans it)s good to go.
Step $: Bend the upper rails
3here are 'arious ways o& doing this. So"e bending &itures are sold with an a!!essory that uses the press to &old the top rails o'er. So"e people si"ply ha""er the" o'er with a ha""er+ woring &ro" one end to the other and then s"a!ing on top o& the die on!e the rails are &olded o'er+ to get out the lu"ps. y partner !a"e !a"e up with the Bworing barB as a great way to ha""er the upper rails o'er without lu"ps. And it wored lie a !ha"p. %t)s ust a long pie!e o& &lat bar with handles welded to it. it. ou ha""er on the woring bar and it translates the &or!e to the rails in a uni&or" "anner to get ni!e s"ooth bends with !risp !orners. 3his re8uires two people. -ne person stands on one side o& the ben!h 'ise and holds the woring bar by the handles so that it)s al"ost &lat on top o& the outside &or"+ with one side o& the &lat bar against the rail on the opposite side o& the 'ise &ro" where he)s standing. 3he other person+ standing opposite the the &irst person+ s"a!s s"a!s the &lat bar+ starting at one end and woring to the other end. @ote that in this pi!ture+ it)s ust being held in pla!e with one hand &or display. display. 3he bar holder needs to be dire!tly behind the 'ise+ holding both pipe handles to align it properly as the ha""er "an "aes ea!h stroe.
3his needs to be done with the bending &iture !la"ped in the 'ise+ not only to eep the sides o& the re!ei'er tight against the die &or a good go od uni&or" bend+ but to eep the die &ro" slipping down in the outside &or". As the upper rails start start to bend o'er+ the person person holding the woring bar needs to eep it at the sa"e angle as the rail until the bar is 'erti!al ("eaning that the rails are laying &lush on top o& the die#. 3he ha""er operator ust wors up and down the woring bar. e used a 5$lb 5$lb sledge ha""er and % &ound it generally too "e 5 stries along the length o& the bar &or ea!h BpassB. A&ter % "ade a pass+ the angle would be !hanged and %)d %)d "ae another pass. %t usually too us passes to get the rails laying down &lat on top o& the die. 3hat)s only 15 ha""er stries on the woring bar &or ea!h rail. hen the rail was laying &lush on top+ we)d "ae "ae one "ore pass B&or good "easureB+ "easureB+ "aing "ore lie stries stries (!loser together# to to ensure uni&or"ity. uni&or"ity. 3he result was superb.
3he tri! is ust to tae your ti"e+ "ae good solid ha""er stries with a hea'y sledge ha""er+ and to eep the woring bar at the the !orre!t angle. And depending on how "any re!ei'ers you)re you)re "aing+ be prepared to ha'e to repair your woring bar. -urs was beat all to hell on the top. % was ha'ing so "u!h &un+ % was 'ery eager on the sledge ha""er. :$# %n retrospe!t+ the woring bar would ha'e been better i& the handles were at about a 120 degree angle &ro" the &lat bar instead o& 90 degrees as ours were. hen striing near the end o& the bar+ % had to be !are&ul not to hit "y asso!iate)s hands as he was holding the handles. So+ i& you want to "ae a woring bar &or the upper rails+ eep sa&ety in "ind. and angle the handles out away &ro" the "iddle where the ha""er will be striing. %t)s also a good idea to ha'e a step stool or so"e way o& getting higher abo'e your 'ise as the angle !hanges on the upper rails. ou don)t want to to be swinging a sledge ha""er that high. et abo'e it so you ust ha'e to li&t it and "ostly let gra'ity do the ob when it)s at that that angle. %t)ll "ae the ob a lot easier and you)ll get "ore uni&or"+ solid blows. And this is one o& the steps where &atigue will get you. % busted "y nu!le a &ew ti"es when % was tired and "ade a glan!ing blow o&& the woring bar. Sa&ety &irst+ ya now.
Step %: Remove the die from the outside form
3his is &airly straight&orward. straight&orward. -n!e the upper rails are bent and pass your 8uality !ontrol inspe!tion+ un!la"p the &iture &ro" the 'ise. -pen the aws o& the 'ise a bit wider+ turn the &iture upside down and set it on top o& the aws. 3ae a pie!e o& bar sto! and at least a 5$lb sledge sledge ha""er and ha""er
the die ba! out. %t should start !o"ing out o& the outside &or" and go between the open aws o& the the 'ise. ,ay a pad o& so"e sort in there so i& it it &alls out it won)t get dinged up. =on)t put your hand under there to !at!h it as your buddy ha""ers it outE As "e about how "y &inger got s"ushed when the 5$lb sledge ha""er and the weight o& the die landed on it. And eep in "ind+ when you)re doing this+ you)re ha""ering on the underside o& the botto" plate o& the die. %& your bolts that !in!h up the &lat inside the die are protruding &ro" the botto" o& this this botto" plate (as ours were by ust about 1/B#+ you)ll want to be !are&ul not to hit the" with with your bar sto! when ha""ering out the die &ro" the outside &or".
hen the inside die !o"es out+ you will noti!e that the sides tend to spring ba! ust a tad away &ro" the &or". 3his is nor"al+ and to be epe!ted. %t will be pulled ba! together at the trunnion lo!ations when you build this into an A> ri&le+ with the ri'ets or s!rews (or whate'er you)re using#+ as well as at the !enter support. So don)t worry about it.
ou)ll also see in this pi!ture+ that there is grease where the top rails rails were &olded o'er. 3his "aes a handy gauge o& your upper rail bending pro!edure. %& you properly greased the area+ it will s8uee7e the grease out when the upper rails are tight on the top o& the die.
Step &: Remove the receiver from the die
So now the die is out o& the outside &or". &or". ou !an re"o'e the bolts to un!la"p the re!ei'er &ro" the the die+ whi!h should release the botto" botto" plate. ou)ll also noti!e that+ oddly enough+ your your &lat a!tually loos a lot lie an A> re!ei'er.
@ow+ the botto" plate is released and you si"ply need to re"o'e the die &ro" inside the re!ei'er. 3he ni!e thing about the bending &iture we used was that the top o& the die had a raised strip down the "iddle that was parallel with the botto". So this "ade a handy pla!e to !la"p in a 'ise as shown below+ and tae another pie!e o& bar sto! and tap the re!ei'er o&& the &or" slowly+ "aing sure not to de&or" any "etal. %& you greased it properly+ it should !o"e o&& with little little e&&ort and only light taps. e tapped on the rear end o& the re!ei'er where it)s a ni!e wide bearing sur&a!e+ to "ini"i7e any proble"s.
Summar' and miscellaneous comments
3hat)s itE ou)re doneE ou should ha'e a bent re!ei'er now. ipe o&& all the grease and get to building your A>. As % said at the beginning+ this pro!ess should tae 15$20 "inutes on!e you get the hang o& it. 3he really hard wor is already done &or you i& you)re you)re using a 3ap!o &lat that already already has all the holes in it. % !hose to use &lats that didn)t ha'e trunnion holes in the" already be!ause o& the "ethod %)" going to use &or "ounting "y trunnions will be di&&erent. 4ut the pre!ision part o& &abri!ating a re!ei'er is all in the &lats and the bending ig. %t)s al"ost idiot$proo& (noti!e (noti!e % said Bal"ost :$# #. 4e&ore % wrap this up+ % do want to point out a &ew other things. A lot o& builders that ha'e bent their own &lats ha'e noti!ed stret!hing/distortion stret!hing/distortion around the "ag well well opening. 3his is presu"ably be!ause there isn)t really any "etal on the botto" o& the re!ei'er in that area+ and as it bends in the &iture+ it pulls up on the sides. % did not noti!e any distortion distortion o& the "ag opening whatsoe'er. %t si"ply wasn)t an issue &or us. 3he design o& the &or" (with two bolts through the "ag well whi!h put a good bind on the "etal on either side o& the opening# plus !opious a"ounts o& grease in the &iture ept it &ro" e'er being an issue. Another !o""on issue is elongation o& the trigger pin ($ais# hole. And we did see that on our re!ei'ers. 4e!ause that hole is so !lose to the !orner+ the botto" o& the is on the bend+ and there isn)t any "etal abo'e it be!ause o& the hole+ so it doesn)t bend lie the rest o& the re!ei'er. 3his leads to the trigger pin hole ha'ing a BdipB at the botto". ou !an see it in the &irst pi!ture o& Step < o& "y tutorial+ abo'e. 3his is easily &ied by woring the "etal gently with a ha""er around the botto" botto" !orner be&ore tapping it o&& o& the die. e !hose not to worry about it be!ause it)s an o'ersi7ed o'ersi7ed hole anyway+ so it)s inherently stronger stronger than the s"aller s"aller hole on the other side already. already. lus it)ll be heat treated. And the pin isn)t going to be loose in the hole or anything+ as the distortion is relati'ely relati'ely "inor there. %t)s really "ostly "ostly ust a !os"eti! issue issue as &ar as % !an tell. %& it bothers you+ round it o'er with a ha""er and wor it it ba! to the original shape shape o& the hole. @o biggie. 3ools. 3o bend a &lat+ &lat+ you)ll need so"e so"e basi! tools or at least a!!ess to the". the". -b'iously+ you)ll need a shop press. 3he 20$ton "odel &ro" &ro" ;arbor Freight wored lie a !ha"p. !ha"p. A 12$ton should do it too+ % hear. % e'en thin it !ould be done by hand+ with a de'i!e %)'e designed. %t will be undergoing testing possibly in the the near &uture+ but "ore on that later. For now+ the sa&e bet is using a press. %t "aes short wor wor o& it. ou)ll also need a good solid "ounted 6B ben!h 'ise. % !ouldn)t see doing it with a s"aller one. All the ha""ering and !o"pressing !o"pressing that)s needed &or this this using the 'ise+ a s"aller one would be !hallenged to get the ob done. G'erybody needs a 6B 'ise anyway+ so ust ust buy one. ;arbor Freight is is your &riend. &riend. 3hen there is the woring bar+ i& you !an get one "ade or "ae "ae one yoursel&. %t sa'es a lot o& ti"e and trouble trouble %;-. ;a""er$wise+ we did pretty "u!h "u!h e'erything with a 5$lb sledge (bending the upper rails and re"o'ing the die &ro" the outside &or"# and a $ pounder &or lighter wor lie no!ing o&& the re!ei'er &ro" the die. A plain$ane so!et set &or the bolts on the die. A !an o& grease and ,G@3 o& shop rags+ as well as degreaser. 4ut what !a"e in the "ost handy was "is!ellaneous bar sto!. e used it &or shi""ing the ra" on the press when repositioning to the ends o& the die+ we used it &or ha""ering the die out o& the &or"+ we used it &or ha""ering the re!ei'er o&& the die+ and we used it &or shi"s in !ases where we had pushed the die too &ar into the &or" and needed need ed to push it ba! up and botto" it out against the botto" plates o& the &or". % highly re!o""end ha'ing so"e pie!es o& bar sto! laying laying around+ o& 'arious si7es and shapes.
So that should pretty "u!h !o'er "y eperien!e with bending &lats and detail how to use this parti!ular bending &iture. i'e it a whirl and enoy yoursel&.
